J. Everett Dutschke, 41 years old, of Tupelo, Miss., was charged with possessing a toxin for use as a weapon, among other charges, the U.S. attorney's office said. He is scheduled to appear in federal court in Oxford, Miss. on Monday.

Mr. Dutschke was taken into custody without incident, according to an FBI spokeswoman. The arrest follows a tumultuous week in which the man initially charged with sending the letters, Paul Kevin Curtis, a 45 year-old Elvis impersonator who had quarreled with Mr. Dutschke, was released after evidence and testimony in federal court led investigators to focus on Mr. Dutschke.

Previously

Mr. Dutschke, a martial-arts instructor, rock musician and failed political candidate, allowed FBI agents to search his home and his business this week. His attorney, Lori Nail Basham, said earlier this week that he was cooperating fully. Later in the week, investigators searched places that Mr. Dutschke recently visited.

April 22 -- Charges against Mr. Curtis are dropped and he is released from jail. Law-enforcement officials say they are tracking and investigating another individual, J. Everett Dutschke, for links to the crime. Lawyers for Mr. Curtis indicate in court testimony they believe Mr. Dutschke framed their client.

April 24 -- Federal authorities search Mr. Dutschke's home and former business in Tupelo, Miss., in connection with the letters.

Letters addressed to President Obama and the U.S. Senate have tested positive for ricin. How does ricin kill people? Where does ricin come from? Who has used it as a weapon? WSJ's Jason Bellini has "The Short Answer." Photo: Getty Images

Ricin-laced letters were sent April 8 to U.S. Sen. Roger Wicker (R., Miss.), President Obama and Sadie Holland, a local county judge. No one was injured, but ricin may be fatal if ingested. News of the letters came about the same time as the April 15 bomb attacks at the Boston Marathon, leading to speculation that the two acts were part of a coordinated terrorist plot.

On April 17, FBI agents arrested Mr. Curtis, of Corinth, Miss., in connection with the letters. Sections of the letters contained phrases that Mr. Curtis had used in some posts online and the letters were postmarked from Memphis, which handles mail from northeast Mississippi. Mr. Curtis, however, professed his innocence and told investigators that he believed he could have been set up by enemies, possibly Mr. Dutschke.

Mr. Dutschke has been in a feud, mostly online, with Mr. Curtis for at least several years, over a range of subjects, from their musical talents to membership in Mensa, a group for highly intelligent individuals. Lawyers for Mr. Curtis indicated in the court testimony they believe Mr. Dutschke framed their client.

The pair worked together briefly at the Tupelo insurance agency of Mr. Curtis's older brother, Jack, and may have had a falling out over plans for Mr. Dutschke to publish in his newsletter information from Mr. Curtis about what Mr. Curtis alleges was a scheme by a northern Mississippi medical center to traffic in human body parts and organs, according to the court testimony.

Mr. Dutschke was also arrested in January on state child-molestation charges involving three girls under the age of 16. Those cases are pending. His attorney said he had pleaded not guilty.

Mr. Dutschke, the owner of Tupelo Taekwondo Plus, ran as a Republican for the state House of Representatives in 2007 and lost. The Democratic incumbent whom he challenged was the son of the judge who received a ricin-laced letter.

Mike Maynard, chairman of the Lee County Republican Party, recalled Mr. Dutschke could be "a little overbearing. He could be very intense and then just disappear."

In one instance, Mr. Dutschke became incensed that someone kept taking down a campaign sign for Haley Barbour, who was running for governor, Mr. Maynard recalled. Every day Mr. Dutschke would put a new sign up only to find it removed, until one early morning Mr. Dutschke waited in his car near the location to catch the perpetrator in the act. He filmed the individual removing the sign and followed him in his car.

"He chased him into town," said Mr. Maynard. And "there were some words."

The U.S. attorney's office said in a statement that Mr. Dutschke was charged "with knowingly developing, producing, stockpiling, transferring, acquiring, retaining and possessing a biological agent, toxin and delivery system for use as a weapon, to wit: ricin, and with attempting, threatening and conspiring to do the same." The federal criminal charges carry a maximum penalty of life imprisonment, the statement said.

This copy is for your personal, non-commercial use only. Distribution and use of this material are governed by our Subscriber Agreement and by copyright law. For non-personal use or to order multiple copies, please contact Dow Jones Reprints at 1-800-843-0008 or visit www.djreprints.com.